In the production of ink jet printheads, a cavitation layer is typically provided as an ink contact layer. The cavitation layer is needed to prevent damage to the underlying dielectric and resistive layers during ink ejection. As ink is heated in an ink chamber by a heater resistor, a bubble is formed that forces ink out of the ink chamber and through an ink ejection orifice. After the ink is ejected, the bubble collapses causing mechanical shock to the thin metal layers comprising the ink ejection device. In a typical printhead, tantalum (Ta) is used as a cavitation layer. The Ta layer is deposited on a dielectric layer such as silicon carbide (SiC) or a composite layer of SiC and silicon nitride (SiN). In the composite layer, SiC is adjacent to the Ta layer.
Under NMOS printhead chip manufacturing process conditions, there is sufficient adhesion between the Ta layer and the SiC layer. However, due to higher processing temperatures such as for printhead chips produced containing CMOS devices, delamination between the Ta layer and the dielectric layer becomes a significant problem. If the cavitation layer delaminates from the dielectric layer, ink will penetrate into cracks and corrode the dielectric layer and underlying heater layer which will result in heater failure. In addition, heat transfer from the heater film to the ink will be degraded, thereby adversely affecting print quality. Accordingly, there is a need to provide thin film structures for ink jet printheads that have increased adhesion between the cavitation layer and underlying dielectric layer.